The greatest problem associated with reciprocating pumps located in oil wells is due to sand or debris collecting in the pump valves and the jarring of the pump to clear the debris is disclosed in U.S. Pat. No. 2,351,576 of Thigpin. This patent discloses the use of a spacer member 20 which is positioned above the cross-head and which may be pivotally mounted to be positioned between the upper surface of the cross-head 10 and clamp 15 attached to the polished rod 11 to assist in carrying out the "bumping procedure" to clear the pump valves. As disclosed in U.S. Pat. No. 2,351,576, accumulation of sand or other debris hinders the operation of the reciprocating pump, particularly the valves therein, and rather than removing the sucker rod string and the pump from the well for cleaning and adjustment, the string is jarred in a procedure commonly referred to as "tagging bottom". The disclosure in the Thigpen patent, referred to as a "bumping" procedure, is the same "tagging bottom" procedure for jarring the pump, especially the valves in the reciprocating pump located in the well.
Spacers have been used for other purposes when located between the upper surface of a bridal head and a clamp attached to a polished rod such as disclosed in U.S. Pat. No. 3,251,310. In this patent a spacer is used so that a dynamometer may be inserted between the upper surface of the carrier bar and the clamp on the polished rod.
U.S. Pat. Nos. 2,877,652; 4,296,678; and 4,653,383 all disclose hydraulic cylinders which change or increase the stroke of the polished rod normally raised and lowered by a connector cable of an oscillating horse head for operating a sub-surface oil well pump. Each of these patents disclose an extensive and expensive system to change the stroke of the polished rod.
All of these patents require extensive or expensive equipment, such as a hydraulic system to make the change in the stroke of the polished rod, or that the person making the change be subject to the danger of a fall or being hurt by the equipment since the change must be done at a significant height so that the person must make the change off the ground. In the system of the present invention, the use of a spacer which may be easily inserted or removed by a person standing on the ground overcomes the dangers of the prior art and permits the light weight spacers, which is a feature of the present invention, to be quickly and easily used.